**6. Effect of chitosan on microbial diversity in UASB treating POME under thermophilic condition**

Palm oil mill effluent (POME) contains high COD and biochemical oxygen demand (BOD). POME consists of a wide range of biological substances from complex biopolymers such as proteins, starches and hemicelluloses to simple sugars and amino acids. POME may also contain dissolved oil and fatty acids, glycerin, crude oil solids and short fibers as well as soluble materials that are harmful to the environment. Since POME is discharged at high temperatures (80–90oC), both mesophilic and thermophilic temperatures have been widely applied for POME treatment by anaerobic digestion.
